Answer: Both I-1 & I-2 are heterozgous. A cross between two hetrozygous produces homozygous dominant (1/4), heterozygous (1/2) and homozygous recessive (1/4) The fraction of heterozygous progeny out of 3/5 = (1/2) /(3/5) = 1/2 * 3/5 = 3/10 Solution Answer: Both I-1 & I-2 are heterozgous. A cross between two hetrozygous produces homozygous dominant (1/4), heterozygous (1/2) and homozygous recessive (1/4) The fraction of heterozygous progeny out of 3/5 = (1/2) /(3/5) = 1/2 * 3/5 = 3/10.